1. Field of the Invention
This invention relates generally to the field of medical equipment for respiratory therapy and more specifically to the user interface for a ventilator used for monitoring and controlling the breathing of a patient.
2. Description of the Related Art
Modern patient ventilators are designed to ventilate a patient""s lungs with breathing gas, and to thereby assist a patient when the patient""s ability to breathe on his own is somehow impaired. As research has continued in the field of respiration therapy, a wide range of ventilation strategies have been developed. For example, pressure assisted ventilation is a strategy often available in patient ventilators and includes the supply of pressure assistance when the patient has already begun an inspiratory effort. With such a strategy, it is desirable to immediately increase the pressure after a breath is initiated in order to reach a target airway pressure for the pressure assistance. This rise in pressure in the patient airway which supplies breathing gas to the patient""s lungs allows the lungs to be filled with less work of breathing by the patent. Conventional pressure assisted ventilator systems typically implement a gas flow control strategy of stabilizing pressure support after a target pressure is reached to limit patient airway pressure. Such a strategy also can include programmed reductions in the patient airway pressure after set periods of the respiratory cycle in order to prepare for initiation of the next patient breath.
As patient ventilator systems and their various components, including sensors and control systems, have become more sophisticated, and more understanding is gained about the physiology of breathing and the infirmities and damage which form the requirements for respiratory therapy, the number of variables to be controlled and the timing and interrelationships between the parameters have begun to confront the caregiver with a daunting number of alternative therapeutic alternatives and ventilator settings. Also, in such a complex environment, the interface between the ventilator and the caregiver has often not been adaptable to the capabilities of the operator, thus running the chance of either limiting the choices available to a sophisticated user or allowing a relatively less sophisticated user to chose poorly from the alternatives presented. Thus, it would be beneficial if a ventilator interface guided the user through the setup or therapy modification process, illustrating the relationship between changes, preventing incorrect or dangerous settings and sounding alarms or other audible indications of invalid settings when something is about to done that exceeds limits, but also allowing the advanced and sophisticated user to gain access to the full range of ventilator capabilities through an interface which both presents the various parameters and allows the visualization of their relationships.
Clinical treatment of a ventilated patient often requires that the breathing characteristics of the patient be monitored to detect changes in the breathing patterns of the patient. Many modern ventilators allow the visualization of patient breathing patterns and ventilator function and the caregiver adjusts the settings of the ventilator to fine tune the respiratory strategy being performed to assist the patient""s breathing. However, these systems have been, up until now, relatively difficult to use by the unsophisticated user unless a limited number of options are selected. For example, in one prior art system, only a single respiratory parameter may be altered at a time. Moreover, the various respiratory parameters must often be entered into the ventilator controller in a prescribed order, or, where no order is prescribed, certain orders of entry should be avoided, otherwise the intermediate state of the machine before entry of the remaining parameters may not be appropriate for the patient. This inflexible approach to ventilator setup requires additional time and training if the user is to quickly and efficiently use the ventilator in a critical care environment.
Previous systems have also been deficient in that it is often difficult to determine the underlying fault that has caused an alarms to be sounded, and what controls or settings should be adjusted to cure the problem causing the alarm. For example, prior alarm systems have consisted of nothing more than a blinking display or light with an alarm to alert the user that a problem existed. Similarly, many prior art systems provided only limited assistance to a user or technician in setting the parameters to be used during treatment. For example, if a technician attempted to enter a setting that was inappropriate for the patient because of body size or for some other reason, the only alarm provided may have been an auditory indication that the value was not permitted, but no useful information was provided to assist the technician in entering an appropriate setting.
One problem consistently presented by prior art ventilator control systems has been that the user interface has offered relatively little to guide and inform the user during the setup and use of the ventilator. Prior systems typically utilized a single visual display of the operating parameters of the ventilator and sensed patient parameters. Alternatively, prior systems may have numerous fixed numeric displays, certain of which may not be applicable during all ventilation therapies. Even when more than one display has been provided, users typically received limited feedback, if any, from the control system indicating the effect that changing one particular setting had on the overall respiratory strategy. If a parameter was to be adjusted, the display would change to display that particular parameter upon actuation of the appropriate controls, and allow entry of a value for that parameter. However, the user was provided with no visual cue as to how the change in the parameter value would effect the overall ventilation strategy, and thus had no assistance in determining whether the value entered for the parameter was appropriate for the patient.
What has been needed and heretofore unavailable in patient ventilators is a user friendly graphic interface that provides for simultaneous monitoring and adjustment of the various parameters comprising a respiratory strategy. Such an interface would also preferably guide sophisticated users in implementing ventilation therapies, provide guidance on the relationships between parameters as they are adjusted, allow rapid return to safe operation in the event that an undesirable strategy was inadvertently entered, provide alarms that are easily understood and corrected and present all of the relevant information in an easily understood and graphic interface. The present invention fulfills these and other needs.
Briefly, and in general terms, the present invention is directed to a graphic user interface system for controlling a computer controlled ventilator to provide respiratory therapy to a patient. In a broad aspect of the invention, the invention includes a digital processor, a touch sensitive display screen and entry means cooperating to provide a user-friendly graphic interface for use in setting up and carrying out a wide variety of respiratory therapies. The processor controls the displaying of a plurality of screens, including user selectable graphic on-screen buttons for setting the values of various ventilator operating parameters for controlling the ventilator. Depending on the on-screen button touched, the processor causes different graphics to be displayed on the screens, provides graphic representations of the effect on the overall respiratory strategy caused by changes to the settings, and may also provide displays of patient data, alarm conditions, and other information.
In one preferred embodiment of the invention, the system includes the use of a digitally encoded knob for altering selected and displayed values of ventilation parameters, with the acceptable values indicated and unacceptable values alarmed and/or limited to prevent harm to the patient. The digital encoded rotation of the knob may be analyzed by the processor and a magnification factor applied to the knob output to increase the speed with which displayed values are altered. The magnification factor may also be used in the event of an overshoot condition to assist a user in recovering from the overshoot.
In another preferred embodiment of the invention, the processor may detect the connection of a patient to the ventilator when the ventilator is powered-up. The processor may then, in response to such a detection, start up the ventilator using a predetermined set of ventilator control settings deemed to be safe for the widest possible variety of patients.
In a further preferred embodiment of the invention, the processor may only display ventilator control settings appropriate for a selected mode of ventilation. The ranges of values of the appropriate settings, or bounds of the ventilation, may be limited by the processor in response to the selected mode of ventilation such that only those values determined to be appropriate are displayed, thus limiting the opportunity to select incorrect settings. Additionally, the processor may be responsive to specific values entered for certain of the ventilator settings to adjust the ranges of values allowed for ventilator settings dependent on the certain settings. Further, the processor may be programmed to require that a so called xe2x80x9cideal body weightxe2x80x9d be entered before beginning ventilation of a patient, and then only ranges of values for settings that would be appropriate for ventilation of a patient with that ideal body weight are displayed.
In another presently preferred embodiment of the invention, the graphic user interface system includes at least two touch sensitive screen displays, a plurality of manual parameter controls, including at least one control knob that is activated upon selection of a parameter to be controlled and displayed on the screen, and a microprocessor controller which controls the logic and arrangement of the screen displays and the interface with the ventilator. The system of the invention includes protocols programmed into the microprocessor for entry of parameters within ranges predetermined to be appropriate for the patient parameters entered, alarms and other audible indications of invalid entry associated with entries outside of the acceptable ranges of parameters or inappropriate operation such as startup with a patient connected to the ventilator, and the ability to lock selected parameters while allowing for user variation of other parameters.
In another presently preferred embodiment of the invention, the user is provided a graphic interface in which the user is allowed to view and adjust a variety of alarm limits and is able to vary the levels at which the alarms are set off, within limits that are preset by the programming of the microprocessor as representative of values that are not to be exceeded, either as a function of ideal body weight or general parameters for all patients. The resultant setting of a filtered set of alarms may then be used by the user to avoid the setting of parameters that are likely to result in patient distress or other problems with the therapy, while still allowing the sophisticated user to configure a therapy that is customized for the particular patient.
In one presently preferred embodiment, the invention also allows the user an xe2x80x9cundoxe2x80x9d option in which a previously successful setting is reestablished after the user realizes that a series of proposed changes are likely to unworkable for the patient.
In yet another presently preferred embodiment of the invention, the user is provided with alarm indicators indicating the severity of a particular alarm. Alarm messages are also displayed in a selected screen area of the graphic user interface to assist the user in alarm recognition and understanding. Each alarm message may comprise an identifying message identifying the alarm being indicated, an analysis message providing information about the condition that caused the alarm to be indicated, and a remedy message suggesting steps that may be taken by the user to correct the alarm condition.
In a further currently preferred embodiment of the invention, the processor allows the user to configure the graphic user interface to provide a display of the current and/or proposed breath parameters and a graphic representation of the breath timing controlled by those parameters. Such a display allows the visualization of relationships between breath parameters, and, while parameters are being changed, provides the user with a visual representation of the effect of the proposed changes on the ventilation strategy while simultaneously allowing the user to view current settings, thus allowing the user to simultaneously view xe2x80x9cwhere they are nowxe2x80x9d and xe2x80x9cwhere they are going to be.xe2x80x9d
From the above, it may be seen that the present invention represents a quantum leap forward in the user interface available for patient ventilation. While assisting the sophisticated user in both visualizing the ventilation strategy and performance of the patient on the ventilator, it also guides and controls the less sophisticated user in setup and understanding of the relationships between ventilator settings. The invention provides these benefits while enforcing fail-safe functioning in the event of a variety of inadvertent or erroneous settings or circumstances.